An isochrone shows everywhere you can reach from a location within a set time, by a given mode of transport. It’s a more realistic catchment or trade area than a simple distance radius. You might use isochrones to:
count the customers within a 45-minute drive of each of your stores
find which office location gives most employees a commute of an hour or less
measure the workforce within reach of possible real estate sites
In this example we create 60-minute public transport isochrones around ten city-centre locations across England and Wales.
1. Add your locations
Our locations are in an Excel file, with a latitude and longitude for each. Add it with Map > Add Data > XY Point Data, using longitude as the X field and latitude as the Y field.
2. Create the isochrones
Open Isochrone Custom from the Custom toolset of the TravelTime toolbox. In this example we use:
Locations: the ten locations, with City as the ID field
Travel Mode: public_transport
Departing / Arriving: arrival, at 12:00, in the time zone of your locations
Travel time (in minutes): 60
Result Aggregation controls what you get back:
NORMAL: one isochrone per location
UNION: one shape covering everywhere reachable from any location
INTERSECTION: only the area reachable from every location
For large numbers of locations, Isochrone Core is much faster, with a maximum travel time of 180 minutes. For a few individual addresses, the Quick Isochrone tool in the TravelTime tab is quicker still. See How to use the quick tools in ArcGIS.
3. View the result
Run the tool. A new layer shows the area you can reach each city centre from within 60 minutes by public transport.
Population in each catchment: to find how many people live within each isochrone, use Data from Locations with the Demographics layer. It builds the catchments and adds up the population for you. See How to add demographics, places and environmental data to catchments.
Full parameter details are in the Isochrone docs.